Field of the Invention
The present invention relates to an imaging element having a plurality of pixel units, an imaging apparatus using the imaging element, and a method for processing imaging signals.
Description of the Related Art
In an imaging apparatus, there is a process that generates a dynamic range image that is visually wider than a dynamic range image that can be obtained by a single shooting (hereinafter, referred to as an “HDR image”.). A technique is disclosed which configures an imaging element and in which an HDR image is generated by regularly arranging pixels having different aperture ratios (Japanese Patent Application Laid-Open Publication No. 2003-179819). Additionally, in a configuration of an imaging apparatus that enables obtaining images of different viewpoints by a single shooting, a pair of object images formed by a luminous flux that has passed through different pupil regions can be obtained. A technique in which focus detection is performed by using a correlation calculation based on the pair of object images that have been obtained is disclosed (Japanese Patent Application Laid-Open Publication No. 2013-072906). Additionally, a technique is disclosed in which an HDR image is generated by using an imaging element having a pupil dividing pixel unit in which a plurality of pixels is allocated to one microlens (Japanese Patent Application Laid-Open Publication No. 2015-144416).
Although the apparatus disclosed in Japanese Patent Application Laid-Open Publication No. 2013-072906 performs focus detection by using the imaging element having the pupil dividing pixel unit in which the pixels are allocated to the one microlens, Japanese Patent Application Laid-Open Publication No. 2013-072906 does not disclose the process that generates an HDR image. Additionally, the apparatus disclosed in Japanese Patent Application Laid-Open Publication No. 2015-144416 generates an HDR image by combination of pixels each having different aperture ratios with respect to the microlens. In this method, if phase difference detection is performed by using pixels that largely obstruct light rays and signals that cause highlight-detail loss, accuracy in the phase difference detection may be lowered.